When designing lighting devices such as, for example, backlighting devices it is sought to achieve an adequate level of color mixing and luminosity.
This need may arise for example in the case of lighting devices where light-emitting diodes (LEDs) are used as a light radiation device.
One way of reducing the cost of the lighting or illumination device is to provide the manufacturer with a wide choice of LEDs. This approach, however, raises critical issues with regard to mixing of the colors.
The inventors have ascertained that conventional solutions for solving this problem are based, for example, on the use of integrating spheres associated with the radiation sources. This solution, however, inevitably has a low optical efficiency owing to the high number of reflections required to achieve a suitable color mixing level.
It is also possible to use relatively complex optical systems which, in addition to the drawbacks associated with the complexity, including the cost, also have the drawback of having relatively large overall dimensions.
There also exist solutions based on the use of specific LED packages and a given number of light sources. These solutions, however, are not very flexible and are not suitable for possible future developments in terms of an increase in the LED efficiency or use of different light sources.